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"Uncemented femoral components don’t work in osteonecrosis."
Completely uncemented hip resurfacing has the highest success rate in the published literature for osteonecrosis at 99% 15-year implant survivorship.
Osteonecrosis is chiefly a disease of young men. The most common cause is high alcohol consumption. It can also be caused by high doses of corticosteroids (not testosterone) or major trauma such as a fracture or dislocation (not a slip and fall). The blood flow to the head is decreased and a section of the head dies and collapses. This results in severe pain.
Hip resurfacing with a cemented femoral head is somewhat more durable than THR, but completely uncemented HRA has the best outcomes. My 10-year implant survivorship improved from 85% to 99% after adopting the uncemented femoral component.
Many hip resurfacing surgeons remain skeptical because they think bone in growth does not work in a head that is dead. This is true, but neither does cement. Obviously, the head is still alive if we can anchor an implant to it for over 10 years. The problem with osteonecrosis is that there is a large dead segment which creates a bone defect under the implant.
The remaining bone is very much alive and even bleeds vigorously. It still seems to be trying to heal the dead collapsed portion. Filling the defect with cement can cause more surrounding bone death and lead to failure. Cement cures in an exothermic reaction, a big bolus of cement in a big defect can cook the surrounding live bone. The same can occur in cases of osteoarthritis with large cysts (holes in the bone).
With the uncemented implant, I can always achieve a good initial press-fit on the remaining live bone. I graft the defect with bone shavings harvested from the socket preparation. The hypervascular remaining live bone readily grows into the uncemented component. That’s why my implant survivorship has improved so much. Because it works so well, I can now take on ever more severe cases with up to 50% of the head missing due to necrosis.